Starkey, JohnMoussaid, HassanBoucher, DarryelBobicki, Erin R....
7页查看更多>>摘要：Comminution circuits are composed of multiple unit operation, with the objective of reducing mined rock to a size where valuable minerals grains are liberated from gangue. Optimal comminution is critical to achieve efficient mineral separation.& nbsp;There are three reasons for writing this paper. For operators to manage good operations; for designers to produce workable designs; and for educators to provide useful education for mineral process engineers. In all cases, understanding of the transfer size (T-80) between the SAG mill and the ball mill is critical to achieve best economics in a semi-autogenous mill (SAG) grinding plant.& nbsp;T-80 is important to operators because when the SAG energy and the Bond Ball Mill Work Index on SAG ground ore are measured, accurate prediction of future throughput in any SAG circuit is possible. Without knowledge of the plant T-80, it can take many months to figure out how to correct what is really a SAG mill grinding problem, because that problem is hidden if the T80 is not measured.& nbsp;Best Practice Comminution means running a SAG mill under optimal conditions, and avoiding overloading, overspeeding and using excessive steel additions, both during the design and operating stages of the plant. When normal limits for these parameters are exceeded in the design stage, production shortfalls will result, and operating costs will be high. While extra SAG mill capacity is a bonus, lack of capacity is a disaster.& nbsp;This paper shows how to design workable grinding circuits on a particular ore, using either single stage SAG milling, SAB grinding, SABC grinding, or HPGR pre crushing followed by ball milling. There are many ways to set up a SAG plant, and future expansion should always be considered at the design stage. This opportunity can be overlooked if the designer does not understand the options available.
原文链接:
NSTL
Elsevier
Wang, HanHan, JeanManica, RogerioQi, Chao...
12页查看更多>>摘要：The presence of copper(II) ions in the process water used in the mineral processing industry has an impact on iron and nickel sulphide mineral flotation in both acidic and alkaline environments. Millerite (beta-NiS) - a nickel sulphide mineral, has been found misreported to Cu concentrate, which negatively impact the performance of Cu/Ni separation. In this paper, we present a fundamental study on the effect of Cu(II) ions on millerite flotation and surface properties in alkaline solutions. Micro-flotation tests indicated that millerite flotation can be acti-vated by conditioning with copper ions prior to KEX addition at both pH 9 and 12. The surface chemistry of millerite in the presence of Cu(II) was studied by mineral dissolution and EDTA extraction tests as well as XPS analysis to probe the underlying activation mechanism. At alkaline pH, the main copper species on millerite surface was Cu(I) sulphide with minor Cu(II) sulphide and Cu(II) oxide/hydroxide. The Cu(I) sulphide arose from the adsorption and reduction of Cu(II) species. Meanwhile, sulphur oxidation was affected upon the reduction of Cu(II) to Cu(I). Monosulphide species (S2-) at the surface was oxidized into disulphide species (S-2(2-)), resulting in less sulphoxy species (SxOy2-). There was no remarkable increase in nickel dissolution and growth in nickel hydroxide passivation layer upon the adsorption of Cu. In essence, copper ion activated millerite flotation under alkaline pH through affecting millerite surface oxidation.
原文链接:- NSTL
- Elsevier
Li, MingdaBussonniere, AdrienXiang, BailinManica, Rogerio...
9页查看更多>>摘要：In many modern industrial applications such as mineral flotation and water treatment, microbubbles have been used as an efficient aid for increasing the collision and attachment efficiencies and enhancing the recovery of valuable fine minerals. One technique to produce such micro-bubbles is to use the hydrodynamic cavitation process when gas cavities in water nucleate under low hydrodynamic pressure. To better understand the cavitation behavior in the presence of solids with different surface properties, we present an experimental study of a multi-phase system. The characteristics of hydrodynamic cavitation with a Venturi tube were experimentally investigated using acoustic detection. The effect of both particle and tube wall surface hydrophobicity and surface structure on the inception of hydrodynamic cavitation were considered. Results demonstrated that particles with lower wettability promoted hydrodynamic cavitation by efficiently trapping gas pockets that facilitate bubble nucleation. In addition, in the condition of low particle concentration (5 g/L) and fine particle size range (D50 < 20 mu m), parameters including size and roughness did not play a critical role in affecting cavitation inception. Finally, tests using Venturi tubes of different surface properties showed that the wall surface behaves similarly as particles. Hydrodynamic cavitation was promoted by a more hydrophobic Venturi tube which screened the effect of particle surface properties.
原文链接:- NSTL
- Elsevier
Stander, Helene-MarieHarrison, Susan T. L.Broadhurst, Jennifer L.
17页查看更多>>摘要：Coal mining in South Africa is an important economic activity but it generates large volumes of pyrite-bearing wastes in the form of fine coal slurry and discards. These pose a significant acid rock drainage risk. Researchers at the University of Cape Town have developed a multi-stage separation process which separates the coal slurry into different fractions: saleable coal, a sulfide-rich fraction, and a sulfide-lean fraction. This was done with a view to enhancing the material value and producing streams suitable for down-stream re-purposing to avoid disposal and concomitant environmental risks.This paper explores the potential for using sulfide-enriched fine coal waste to ameliorate calcareous (enriched in calcium carbonate) and alkaline soils in the South African context, through a pre-feasibility study focusing on technical viability, local market applications and mine-to-market transport costs. Consideration is also given to direct environmental and safety risks and potential local commercial partners. The analysis shows that the solution is likely to be technically feasible, with potential markets in the livestock, field crop and horticulture sectors located in the provinces of the Northern Cape, Western Cape, North West, Free State, Limpopo and Mpumalanga. It was found that fewer than 13 commercial farms could likely be treated with the hypothetical sulfide-enriched coal waste produced in South Africa in a year. The transport costing analysis shows that the solution is likely to be uncompetitive with currently available soil ameliorants, but it may be competitive with waste disposal costs and augments resource effeciency. A research agenda for further development of the solution is put forth.
原文链接:- NSTL
- Elsevier
Scharm, ChristophKuster, FelixLaabs, MarcelHuang, Qiuliang...
15页查看更多>>摘要：With the aim of reducing CO2 emissions in basic industries, the sector of iron and steel metallurgy is also faced with the question of how carbon can be replaced in ore reduction. By means of in-situ observation, this study investigates the direct reduction (DR) of individual iron ore pellets under an atmosphere of hydrogen (H-2) and carbon monoxide (CO) and at temperatures between 800 degrees C and 1100 degrees C at atmospheric pressure. The progress of the reduction, i.e. the phase change and the structural change, is analysed by X-ray diffraction (XRD) and scanning electron microscopy equipped with energy-dispersive X-rays (SEM-EDX). To evaluate the porosities of the pellets, analytical porosimetry is compared to optical porosimetry findings obtained by analysing images of sections in the SEM (hereinafter called SEM porosimetry). Furthermore, the swelling behaviour is evaluated by video analysis and the reduction swelling index (RSI) is determined. The results show a higher reduction progress and a higher RSI under H-2 atmosphere than under CO atmosphere. Higher temperatures lead to faster reduction progress and to significant changes in the structural composition of the reduced pellets.
原文链接:- NSTL
- Elsevier
Zhang, JieZhang, Xu-GangWei, Xiang-XiangCheng, Shao-Yi...
10页查看更多>>摘要：In the flotation separation of copper-lead-zinc complex polymetallic sulphide ores, the separation of chalcopyrite from galena is difficult because both of them have good floatability. Therefore, the development of a green, ecofriendly and selective galena depressant is highly required. In this work, sodium polyaspartate (PASP) was used as a galena depressant in the separation of chalcopyrite from galena. Single mineral flotation experiments showed that PASP could selectively depress galena. With 10 mg/L PASP addition at pH = 10, the recovery of chalcopyrite remained 91.9%, but the recovery of galena decreased to 1.1%. The selective depression mechanism of PASP was studied by collector adsorption measurements, FT-IR and XPS analysis.
原文链接:- NSTL
- Elsevier
Toledo, Ailton Guilherme RissoniTayar, Samir PriotoArena, Fabiana AntoniaBenedetti, Assis Vicente...
21页查看更多>>摘要：A response surface capable of describing the extraction of copper with high statistical confidence (R-2 = 0.9973) was obtained using a central composite factorial design (CCD). The parameters used were the initial concentration of Fe2+ ions ([Fe2+](i)) and pulp density (rho(pulp)). The results evidenced that chalcopyrite leaching was strongly influenced by the solution potential, which was a function of the [Fe2+](i):rho(pulp) ratio. The optimal parameters obtained for maximizing the copper extraction percentage were those that satisfied a ([Fe2+](i):rho(pulp) ratio of asymptotic to 80 (mmol L-1/%), in the range from 200 to 398 mmol L-1 of Fe2+. The [Fe2+](i):rho(pulp) ratio of asymptotic to 80 allowed an optimal range of solution potential for most of the experiment duration, which provided a copper extraction of 91 +/- 3% in 28 days, under moderate conditions. The leaching residues were analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray diffractometry (XRD), and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS). The mathematical model, together with the calculated Nernst potentials of the main oxidation-reduction reactions of chalcopyrite, indicated that the copper extraction was governed by experimental conditions that favored chalcopyrite reduction coupled with the chalcocite oxidation reaction. Hypotheses to explain the reasons for certain experimental conditions that could increase or decrease chalcopyrite dissolution were formulated and are extensively discussed. These findings contribute to the development of new routes for the processing of chalcopyrite mineral.
原文链接:- NSTL
- Elsevier
Zhang, YeXu, RuiWang, LiSun, Wei...
11页查看更多>>摘要：In this study, a struvite-precipitation method that uses triammonium phosphate trihydrate was introduced to separate Mg2+ from Li+ in a salt-lake brine. The precipitation experiments in the simulated brines exhibited excellent Li/Mg separation efficiency. The Mg2+ recovery in the precipitates, Li(+ )recovery in the solution, and Mg/Li mass ratio in the solution reached 99.71%, 4.88%, and 0.1%, respectively, under optimum condition. The relevant separation and adsorption mechanisms were investigated using solution-chemistry calculations, first principle density functional theory (DFT) calculations, X-ray diffraction (XRD) analysis, scanning electron microscope (SEM) analysis, Brunauer-Emmett-Teller (BET) analysis, and zeta-potential measurement. The solution-chemistry calculations, first-principle DFT calculations, and XRD analysis demonstrated selective Li/Mg precipitation separation. The XRD analysis illustrated that the precipitates were struvite and dittmarite. The SEM, BET, and zeta-potential measurement results demonstrated that Li+ in the solution could adsorb on the magnesium precipitates and suffered from a significant loss during the aging process. Therefore, performing a quick and direct filtration after the precipitation process is necessary to eliminate the Li+ loss in the precipitates. The triammonium phosphate trihydrate also exhibited excellent performance in the simulated salt-lake brines with a broad range of initial Li+ and Mg2+ concentration and actual salt-lake brines.
原文链接:- NSTL
- Elsevier
Silva, KlaydisonLucas, A. SilvaBastos, Leonardo C.Correia, Julio C. G....
12页查看更多>>摘要：This work describes, at a molecular level, the adsorption differences between etheramine and amidoamine N-[3(dimethylamino)propyl]dodecanamide, a conventional silicate collector and one not yet used in industrial iron ore flotation, respectively. The molecular dynamics simulations showed that the adsorption of this amidoamine on the quartz surface, regarding the quartz-hematite system, tends to be more selective than etheramine. The explanation for this behavior is related to the combination of the water coordination at hematite-(D2) surface and the bulky head group of the amidoamine. Regarding the neutral molecules of etheramine and amidoamine, the coordination of water on the surface of hematite-(D2) acts as a shield, making it difficult for collector adsorption. In relation to protonated collector molecules, the combination of the amidoamine head group (with methyl bonded to nitrogen in the tertiary amine) with the water on the hematite-(D2) surface causes steric hindrance, impairing the amidoamine adsorption, while the etherammonium cations manage to adsorb on this hematite surface anyway. Also, the amide group favors hydrogen-bonding between collectors in the adsorption layer, which brings stability to the layer.
原文链接:- NSTL
- Elsevier
Iglesias-Gonzalez, NievesRamirez, PabloLorenzo-Tallafigo, JuanRomero-Garcia, Aurora...
8页查看更多>>摘要：In this work, the recovery of Cu from large waste printed circuit board (PCB) pieces by biogenic ferric sulphate at high solid to liquid ratio was studied. PCB parts were packed in a column and biogenic ferric was constantly recirculated. A high oxidation reduction potential (ORP) decrease was observed in ferric leaching due to ferric ion consumption; this drop caused a slower copper dissolution kinetics. After 25 days, 62.2% of copper was leached from PCBs column. PCBs column was connected to a flooded packed-bed (FPB) bioreactor to study the biological regeneration of ferric ion consumed in chemical reaction. The bioreactor connection enabled working at a constant ORP (700 mV vs. Ag/AgCl) during the whole test time. The improvement of oxidising conditions hugely increased copper dissolution rate, reaching 90% of copper recovery after 25 days. The FPB bioreactor operated continuously without showing inhibition problems and generating a leaching liquor with a high and constant ORP. The novel proposed configuration consists of a chemical reactor, where large PCBs pieces are piled at a high solid load, connected to a FPB bioreactor that regenerates the spent ferric ion enabling the leaching without reagents consumption, is a simple, inexpensive, low energy consumption, eco-friendly and effective system to recover copper from PCBs.
原文链接:- NSTL
- Elsevier
